Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Trade receivables, allowance for doubtful accounts	$ 2,989	$ 3,040
Trade receivables, related parties	10,208	5,534
Prepaid expenses and other current assets	6,000	5,705
Property and equipment, accumulated depreciation	201,240	198,282
Accumulated amortization of Intangible assets	79,117	78,234
Intangible assets subject to amortization, net	15,774	16,656
Accounts payable and accrued expenses	26,271	29,787
Unamortized debt issuance costs	3,054	3,226
Related Parties
Prepaid expenses and other current assets	274	274
Intangible assets subject to amortization, net	13,338	13,918
Accounts payable and accrued expenses	$ 4,017	$ 3,909
Class A common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	260,000,000	260,000,000
Common stock, shares issued	64,755,921	64,477,171
Common stock, shares outstanding	64,755,921	64,477,171
Class B common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	14,927,613	14,927,613
Common stock, shares outstanding	14,927,613	14,927,613
Class U common stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	9,352,729	9,352,729
Common stock, shares outstanding	9,352,729	9,352,729